Tanya, one can of P.A.M. will last a very long time with only one snake. Personally I've heard both sides of the Equate vs Provent-A-Mite debate and it always comes down to this for me.
It's $20.00. That's less than what it costs my family to order in some pizza. That's less than renting some movies, buying chips and soda and sitting home. I can give up one pizza or one night of movies to buy a product tested safe for our snakes. For me that's an easy decision. Sure I have to order it online but it only takes a few days to arrive. I could run over to WalMart and spend that $4.00 but then I might hurt our snakes or I might just lose a night's sleep worrying that pinching pennies could find me waking up to a damaged animal.
It's just not worth it for me, Tanya. I don't put meds in my kids mouths that aren't tested safe for children, I don't spray things around the snakes that aren't test safe for them.